Copying a default page copies the parent with all it's children

Moment ... there is something else going on here. Got the same result with the default page being deactivated.

Maybe it has something to do with the following error, when i tried to rename the id from index to index-bak

Traceback (innermost last):
  Module ZPublisher.Publish, line 138, in publish
  Module ZPublisher.mapply, line 77, in mapply
  Module ZPublisher.Publish, line 48, in call_object
  Module z3c.form.form, line 233, in __call__
  Module z3c.form.form, line 228, in update
  Module plone.app.z3cform.csrf, line 22, in execute
  Module z3c.form.action, line 98, in execute
  Module z3c.form.button, line 315, in __call__
  Module z3c.form.button, line 170, in __call__
  Module plone.app.content.browser.actions, line 168, in handle_rename
  Module OFS.CopySupport, line 334, in manage_renameObjects
  Module Products.CMFPlone.PloneFolder, line 88, in manage_renameObject
  Module OFS.CopySupport, line 355, in manage_renameObject
ResourceLockedError: Object "index" is locked via WebDAV

What I did:

In folder_contents I copied the default page on the start site and pasted it somewhere.

What I expect to happen:

The page should have been pasted in no time.

What actually happened:

The spinner was spinning, the /tmp directory on the filesystem was growing until no space was left (100GB site, 1.7GB /tmp), the action did not complete successfully althouth the folder_contents portal message told me: "Successfully copied items" folder contents message but also "Error performing action" popup.

I suspect, when copying a default page not the default page but the whole site is copied.

What version of Plone/ Addons I am using:

5.1rc2-pending

plone / Products.CMFPlone